Fire grenades shouldn't reflect team damage after a few seconds

I like to use molotovs, they are great for keeping people away. However, occasionally I will kill a teammate, and from then on any damage I do to teammates is reflected to me. I've have numerous occasions where teammates purposely sit in my fires to kill me. Most other times they walk through it for whatever reason. In either case, only the initiation damage from my fire should be reflected to me. Fire should not be reflected if an idiot teammate can't be bothered to move out of the fire, or avoid it entirely. It's super annoying. If you want an example of this in action play some single player with bots, throw a few molotovs, watch them sit in it.

Personally, I would prefer there be no damage reflection at all, and no limit to teamkilling, so that kicks require a vote from players on the server, which would make this a non-issue.
I am not sure how it could be fixed with the existing implementation, other than to remove team damage from fire bombs, which is like some Call of Duty shit.